Does liquid yeast take longer to eat the sugar than dry yeast? We have had a cream ale in primary firmintation for a week now and it is still bubbling. I know its a good thing and I am just letting it do its thing. Does liquid yeast eat longer and slower than dry yeast? is one better than the other?

The 11 gram packs of dry yeast have about twice as many cells (200 Billion) as a pack of liquid yeast (100 Billion). That is when the liquid yeast is fresh, if it is a month old, about 25% of the cells have died. By 2 months, about 25% of what was alive at the end of the first month are dead, and so forth. Dry yeast is very stable over a long time. So, if you don't use a starter to grow up the liquid yeast, it will probably take longer to ferment with the liquid yeast.

Dry yeast is s fine option, with certain advantages, but the selection of yeast is much more limited than what is available in liquid yeasts. It all depends on if the flavor you want from your yeast is available from a yeast available in dry form. For a Cream Ale, or any ale that you want to finish clean and dry, US-05 is a good dry yeast choice, though some prefer the subtle differences of WLP001 or Wy1056.

While the cell number in a pack of dry yeast is just about ideal for 5 gallons of an ale around 1.050, the cell number in even a fresh liquid yeast pack is a little low for a 5 gallon beer at that OG. The number in a fresh liquid pack is what would usually be recommended for an ale around 1.030. A pack of liquid yeast can make a fine beer, but it is pushing the yeast a bit. Starters are strongly recommended when using liquid yeast.

To determine how many cells you need for 5 gallons of an ale (Note: 1 B/L is often preferred over 0.75 B/L, for an ale, and 1.5 B/L is a good density for a lager): OG/4 x 0.75 B/L x 19 L = billions of cells needed

To determine how large a starter to use (with 100 g of DME/L, for 1.036, on a stir plate:(Billions of cells needed - starting cell number) / 150 B/L = Volume of starter needed in Liters

If you don't have a stir plate, you can swirl the starter every time you think of it. That will yield fewer cells:(Billions of cells needed - starting cell number) / 75 B/L = Volume of starter needed in Liters

The starting cell number is 100 Billion/pack x 75% for each month since manufacture.

wingsfan61 wrote:Thanks for the fast reply! Very detailed answer. Hopefully you don't know all this off the top of your head......Can you give me 2-3 books to procure.

Way too much of my head space is taken up by beer information! However, a lot of the science is similar to what I do for a living, which makes it easier to remember. The yeast growth formulas are my own, based on a data analysis I performed on a series of yeast growth experiments, but give results that are similar to the online calculators.

The best all around homebrewing book is John Palmer's How To Brew. I'd recommend that you read that cover to cover. Things are sometimes more complicated than what is summarized there, but it is a great reference that I still use nearly every week.

I used to recommend Designing Great Beers, next, but I think it is getting a little dated. Perhaps Jamil and Palmer's Brewing Classic Styles is currently one of the best ways to learn about the variables that go into different beer styles.

I would also highly recommend Kai Troester's Braukaiser.com website, especially for an all-grain brewer who wants to understand the process in more depth. There is a lot of great information on brewing science, techniques, and results from experiments he has run testing these concepts.